In today's engine control units, the air filling in the cylinders of an internal combustion engine is frequently set via a position of the throttle valve. In general, it is assumed that the mass flow through the throttle valve corresponds to the fresh air mass flowing into the cylinder after the buildup of the intake manifold pressure.
Filling controls usually provide that only the mass flow which is stationarily necessary for reaching the setpoint filling is set at the throttle valve. In an intake manifold/time constant which is a function of the construction of the overall system, the intake manifold pressure reaches the desirable setpoint value, or the cylinder filling which is a function thereof reaches the corresponding filling setpoint value. The intake manifold/time constant is a function of an intake manifold volume, an intake manifold temperature, and an engine aspiration curve and may be arithmetically ascertained from a state equation.
Filling controllers for controlling an air filling in the cylinders of an internal combustion engine aim for influencing the time duration up to reaching the intake manifold pressure setpoint value or the cylinder filling setpoint value in such a way that it is minimal. Previous filling controllers are based on using the mass flow at the throttle valve as a measure for the cylinder filling, which is, however, imprecise since the decisive variable for the cylinder filling, namely the intake manifold pressure during the closure of the inlet valve, is ignored. This means that when the mass flow at the throttle valve is set above or below the stationary setpoint value in a targeted manner, an intake manifold pressure build-up or reduction and thus a filling build-up or reduction may be accelerated. For this purpose, a differential state equation is set up for the time during which the pressure build-up is to take place, a simplification being carried out according to which the instantaneous aspiration value corresponds to the setpoint aspiration value and the instantaneous residual gas quantity corresponds to the setpoint residual gas quantity.
In engines in which the camshaft phase adjustment has a great influence on the aspiration curve of the internal combustion engine, such a simplification is not admissible, however. If the camshaft is in fact adjusted in the case of a simplified procedure, e.g., in the case of a constant filling request, the aspiration behavior changes and therefore the filling. In the current concept, the filling controller is, however, configuired in such a way that it may only intervene if the air filling deviates from the setpoint air filling.